The Science of Sound

The Science of Sound

Exploring the fascinating world of sound waves, vibrations, and their impact on our daily lives.

The Science of Sound

• Sound waves are vibrations that travel through a medium, such as air or water.
• They are mechanical waves that require a medium to propagate.
• Sound waves can be described by their wavelength, frequency, and amplitude.
• They can be reflected, absorbed, or transmitted when encountering different materials.
• Understanding sound waves is crucial in various fields, including music, communication, and medicine.

Mechanical Waves

Trivia: Sound waves are mechanical waves that require a medium to propagate. They cannot travel through a vacuum. However, they can travel through solids, liquids, and gases. Sound waves are created by vibrations and can be heard by our ears. They play a crucial role in communication and the perception of the world around us.

Multiple Choice

What are sound waves?

• Electromagnetic waves that require a medium to propagate

• Mechanical waves that require a medium to propagate

• Waves that do not require a medium to propagate

• Waves that propagate through a vacuum

The Speed of Sound

• Medium: The speed of sound varies depending on the medium it travels through. It is fastest in solids, followed by liquids, and slowest in gases.

• Temperature: Sound travels faster in warmer temperatures due to increased molecular motion.

• Density: Higher density mediums slow down sound waves, while lower density mediums allow for faster propagation.

• Humidity: Moisture in the air affects the speed of sound. Higher humidity levels result in slower sound propagation.

• Pressure: Changes in air pressure can impact the speed of sound. Higher pressure generally leads to faster sound transmission.

The Speed of Sound

The speed of sound varies depending on the medium it travels through. In air, sound travels at approximately 343 meters per second. In water, it travels at around 1,482 meters per second. In solids, such as steel, it can reach speeds of up to 5,960 meters per second. Understanding the speed of sound in different mediums is crucial in various fields, including physics, engineering, and music production.

Density

Density is the factor that affects the speed of sound the most. Sound travels faster in denser mediums. For example, sound travels faster in water than in air. The density of a medium determines how closely packed its particles are, affecting the speed at which sound waves can travel through it.

Multiple Choice

Which factor affects the speed of sound the most?

• Temperature

• Density

• Humidity

• Pressure

Speed of Sound in Steel

Trivia: Did you know that the speed of sound in steel is approximately 5,960 meters per second? That's more than 17 times faster than in air! This high speed makes steel a great material for transmitting sound waves efficiently.

Multiple Choice

What is the speed of sound in steel?

• 343 meters per second

• 1,482 meters per second

• 5,960 meters per second

• 10,000 meters per second

​Properties of Sound

​Sound energy travels in WAVES

Properties of sound waves:

1. speed

2. loudness AKA intensity

3. pitch​

The Science of Sound

• Pitch: The perceived frequency of a sound wave
• Frequency: The number of cycles of a wave that occur in one second
• Higher pitch: Higher frequency
• Lower pitch: Lower frequency

Pitch: Number of Cycles

Trivia: Pitch refers to the number of cycles of a wave that occur in one second. It is not related to volume. The higher the pitch, the higher the frequency of the sound wave. Pitch is an important concept in music and helps determine the melody and harmony of a song.

Multiple Choice

What is pitch?

• The perceived frequency of a sound wave

• The number of cycles of a wave that occur in one second

• Higher pitch means higher volume

• Pitch is unrelated to frequency

The Science of Sound

• Amplitude: The measure of the maximum displacement of a wave from its equilibrium position.
• Loudness: The subjective perception of sound intensity.
• Amplitude and Loudness: Higher amplitudes result in louder sounds.

Sound Intensity

Trivia: Amplitude measures the maximum displacement of a wave from its equilibrium position. It does not measure the subjective perception of sound intensity, the frequency of a wave, or the speed of sound. Amplitude is a crucial factor in determining the loudness of a sound wave.

Multiple Select

What does amplitude measure?

​

• The maximum displacement of a wave from its equilibrium

• Distance from one crest to another

• The frequency of the wave

• The maximum distance from crest to trough

Multiple Choice

Look at the bottom waveform. How many wavelengths are shown?

• 2.5

• 4

• 8

• 16

Multiple Choice

What is transported by a wave?

• air

• energy

• matter

• particles

Multiple Choice

A transverse wave is traveling through an unknown medium as shown in the diagram. How are the particles of the medium vibrating?

• parallel to the y-axis

• parallel to region R

• Parallel to the x-axis

• Parallel to Region Q

Multiple Choice

How could you measure the speed of sound?

• Measure the time it takes for a pendulum to swing

• Measure the time it takes for a ball to bounce

• Measure the time for an echo to return

• Measure the time it takes for a bell to stop ringing

Multiple Choice

What kind of wave requires the particles of a medium to vibrate and transfer energy?

• infrared light wave

• Radio Wave

• Sound Wave

• Visible light wave

Multiple Choice

What happens to the wavelength of a sound wave when the speed increases?

• Wavelength increases

• Wavelength decreases

• Wavelength remains the same

Multiple Choice

Which wave is classified as a mechanical wave?

• microwave

• infrared wave

• sound wave

• radio wave

Multiple Choice

What happens to the frequency of a sound wave when the speed changes as it enters a different medium?

• Frequency increases

• Frequency remains the same

• Frequency descreases

“

SOUND WAVES - compressional waves formed
from vibrating objects colliding with air molecules

▹ Remember compressional waves are made of compressions

and rarefactions.

Multiple Choice

Which type of wave can be a longitudinal wave?

• light waves

• seismic wave

• electromagnetic wave

• surface ocean waves

Multiple Choice

Which list below includes mechanical waves only?

• seismic waves, sound waves, and water waves

• radio waves, sound waves, waves in a rope

• infrared rays, ultraviolet rays, visible light

• seismic waves, microwaves and x-rays

Labeling

Label the wavelength, compression and rarefaction of the longitudinal wave.

Drag labels to their correct position on the image

rarefaction

compression

wavelength

Multiple Choice

The diagram shows a readout from a device that measures sound waves.

How should these waves be described?

• mechanical longitudinal

• compressional electromagnetic

• compressional transverse

• mechanical transverse

5

Speed of Sound -
depends on temperature
and state of medium

▹ Sound travels in solids and

liquids - molecules are closer
together than gas molecules

▹As a medium temp rises,
molecules move faster
conducting sound waves faster.

Multiple Choice

A student listed some properties of waves.

Which properties did the student list incorrectly?

• 3 and 2

• 4 and 1

• 2 and 4

• 1 and 3

Fill in the Blanks

Does sound travel faster through a solid, liquid or gas?

Multiple Choice

Examine the wave.

Which region on this wave would correspond to rarefaction?

• W

• X

• Y

• Z

HUMAN
HEARING

STAGE 2

The middle of the
ear has three bones
called the hammer,

anvil and stirrup

which amplify sound

waves

STAGE 1
Ear gathers

compressional
waves which

vibrate a tough
membrane called

the eardrum

STAGE 3
The inner ear

contains the cochlea

which vibrates

sending auditory
nerve impulses to

the brain

STAGE 4

The brain decodes
and interprets nerve

impulses

Multiple Choice

The diagram shows a cartoon of a sound wave produced while a student is speaking.

What happens to the sound wave when the student speaks louder?

• The amplitude increases

• the wavelength will double

• the speed will increase

• the amplitude will decrease

Multiple Choice

This diagram shows two different ways to represent longitudinal waves.

Which letter corresponds to rarefaction in the waves?

• Z

• X

• W

• Y

PITCH - how high or low a sound seems to be, which is

related to frequency of a sound wave

SUBSONIC

< 20 Hz

HUMANS CAN HEAR

20 - 20,000 Hz

ULTRASONIC

> 20,000 Hz

Multiple Choice

What type of waves might experience rarefaction?

• gamma waves

• x-rays

• Sound Waves

• infrared rays

Multiple Choice

Two sound waves of different frequencies interfere and produce a resulting waveform shown with four points (W, X, Y, and Z) marked on the new wave.

At which point will the sound be the loudest ?

• W

• X

• Y

• Z

Multiple Choice

The students in the diagram are communicating with the cans and string.

Which is the most likely explanation of how the students can hear and communicate using the objects?

• A Mechanical Wave transfers sound through the string

• sound bounces off the can and echoes

• sound travels through the string as an electromagnetic wave

• Transverse wave transfers sound through rope

Multiple Choice

The diagram shows a research vessel using sonar to map the ocean floor.

Upon which basic behavior of sound waves does this technology depend?

• absorption

• compression

• reflection

• refraction

Multiple Choice

As any type of wave travels through a medium, what is true about the particles in the medium?

• The particles of the medium move in a straight line and are carried with the wave.

• the particles of the medium move up and down and are carried with the wave.

• The particles of the medium are not carried along with the wave

• the particles of the medium move back and forth and are carried with the wave.

Multiple Choice

A boy has a cork on his fishing line in a lake. His brother throws a rock in the lake near where he is fishing, and the waves created from the rock splashing cause the boy's cork to bob up and down for over a minute. What is the medium for the waves in this scenario?

• the cork

• the water

• the rock

• the fishing line

Multiple Choice

Through which medium is it impossible to transmit sound waves?

• space

• rock

• air

• water

Multiple Choice

Sound waves travel fastest through

• air

• smoke

• wood

• water

Multiple Choice

A low pitched sound has

• lower amplitude

• lower frequency

• lower wavelength

• lower intensity